It was a test flight of a Trident II D5 missile launched from the USS Kentucky, an Ohio-class ballistic missile submarine operating in the Pacific Test Range off the Southern California Coast.

The Tridents are part of the U.S. strategic nuclear deterrent. In wartime the missiles are armed with eight independently targetable nuclear warheads. The Kentucky and 13 other submarines in the class each carry 24 of the intercontinental-range missiles.

The Twitter-sphere was inundated Saturday evening with inquiries that came from people up and down the Pacific Coast, and as far east as Utah.

Oceanside police contacted the Federal Aviation Administration and were told it had to do with planned Navy activity over Point Mugu, according to a dispatcher.

To the north, the Orange County Sheriff’s Department also reported on Twitter that the sighting was the result of a U.S. Navy test.

“Light seen in OC sky was confirmed through (Santa Ana’s John Wayne Airport) tower to be a Naval test fire off the coast. No further details,” according to the tweet.